In 2020, breast cancer was the most commonly diagnosed cancer, with over two million cases. Among women, it makes up 24.5% of cancer cases and 15.5% of cancer-related deaths. Refraction-based X-ray imaging can overcome the fundamental contrast limit of computed tomography (CT), particularly in soft tissue, but so far has been constrained to high-dose ex vivo applications or required highly coherent X-ray sources, such as synchrotrons.
The sooner the proper therapy can start, and the diagnosis is established, the better the prognosis and the likelihood of survival.
A team of researchers from the Paul Scherrer Institute PSI and ETH Zurich, in collaboration with the Baden Cantonal Hospital (KSB) and the University Hospital Zurich (USZ), have successfully refined the technique used to detect tumors in their early stages to produce considerable more reliable results and be less unpleasant for the patients.
With this, the researchers have significantly improved image resolution while lowering the radiation dose in traditional computed tomography (CT). Therefore, it is possible to identify breast cancer earlier than before if there are little calcium deposits called microcalcifications. This considerably raises the likelihood that affected women will recover.
According to the experts, this technique, based on X-ray phase contrast, could be swiftly used in clinical settings.
Marco Stampanoni, head of the research group at PSI and Professor of X-ray Imaging at ETH Zurich, said, “We still need a little time, but we’ve reached a milestone along the way with our work.”
Researchers use X-ray phase contrast to offer more physical details to the cancer diagnoses. In other words, the images they produce rely on data not considered by traditional X-ray imaging: the signals produced when living tissue scatters and refracts the radiation. Different structures of varying densities cause X-rays to be not only attenuated but also refracted and diffracted in addition to being attenuated. This data can enhance the photos’ contrast and resolution, making even the smallest things easier to spot.
The researchers from PSI, ETH, KSB, and USZ employ grating interferometry (GI), a technique known from physical metrology. In this, three gratings with a few micrometers between their lines are additionally traversed by the X-rays in addition to the object being examined, making additional information visible.
Scientists have published several images demonstrating the advantages of GI computed tomography over conventional X-rays in terms of resolution and contrast.
The X-rays that scientists used in this method can be generated with a conventional X-ray source, and the radiation dose is roughly equivalent to that used for conventional computed tomography of the breast.
Physicist Michał Rawlik, the lead author of the publication, said, “Our goal is to reduce the dose by a factor of two to three while maintaining the same resolution, or to increase the resolution by 18 to 45 percent – in each case compared to conventional X-ray.”
Scientists are further planning to start clinical trials by the end of 2024. Stampanoni states, “If everything goes to plan, we’ll then be able to start developing a commercial device and running studies in selected clinics.”
Cancer screening is anticipated to be much more pleasant thanks to this new technique. The device will be set up so the patient can lie on a couch with cutouts in the chest area while lying on her stomach. The actual tomograph will be hidden from the patient beneath the couch, and its measuring tool will rotate around the breasts to produce a three-dimensional image.
Rahel Kubik-Huch, director of the Department of Medical Services at KSB and Chief Physician for Radiology, who was involved in the research, said, “Phase contrast X-rays make fine details in the tissue visible. This translational project will explore the potential to employ this technique in the early detection of breast cancer. KSB is interested in further advancing the research collaboration with PSI and ETH Zurich. We hope that one day our patients will be able to benefit from these advances.”
- Michał Rawlik, Alexandre Pereira, Simon Spindler, Zhentian Wang, Lucia Romano, Konstantins Jefimovs, Zhitian Shi, Maxim Polikarpov, Jinqiu Xu, Marie-Christine Zdora, Stefano van Gogh, Martin Stauber, Eduardo G. Yukihara, Jeppe B. Christensen, Rahel A. Kubik-Huch, Tilo Niemann, Cornelia Leo, Zsuzsanna Varga, Andreas Boss, and Marco Stampanoni. Increased dose efficiency of breast CT with grating interferometry. Optica. DOI: 10.1364/OPTICA.487795